In a vehicle provided with a motor as a drive source, such as an electric vehicle or a hybrid vehicle, direct-current power of a battery is converted into alternating-current power by an inverter, and the alternating-current power is supplied, to the motor. An output of a motor is controlled by changing a carrier frequency of an inverter in performing electric power conversion. The carrier frequency of an inverter is not uniquely determined with respect to an output of a motor. For instance, when a target output of a motor is set depending on a traveling state of a vehicle, there exist a plurality of carrier frequencies capable of implementing the target output. Conventionally, electric power conversion is performed by a carrier frequency at which motor efficiency is as high as possible (i.e. motor loss is as small as possible) among the carrier frequencies according to the use conditions.
Patent Literature 1 discloses a vehicle provided with a motor as a drive source. The vehicle is configured such that motor loss is increased by temporarily setting a carrier frequency high during a gear shift operation. Thus, motor efficiency is lowered for reducing a torque.